Periodontal Disease (PD) is a chronic inflammatory illness that is linked to multiple systemic diseases including cardiovascular disease, malignancies and adverse pregnancy outcomes. The molecular mechanisms that drive the systemic manifestations of PD remain elusive. The comprehensive characterization of innate and adaptive mechanisms reflecting the plasticity of the systemic immune response to PD would allow for identification of modifiable targets for the development of novel immune therapies that will prevent the local progression and systemic manifestations of PD. Studies of pathogenic mechanisms within the subgingival crevice suggest that subversion of innate microbial defenses by keystone pathogens, such as P. gingivalis (pg), creates a chronic inflammatory nidus and facilitates bacterial dissemination to the periphery. A major impediment to further characterization of these mechanism has been the lack of functional, sensitive, high throughput assays that can characterize this complex inflammatory process. The work proposed here will address this major shortcoming. We intend to harness the power of mass cytometry (CyTOF), a high-dimensional flow cytometry platform that exploits the resolution, sensitivity and dynamic range of mass spectrometry to quantify over 45 parameters on a single-cell basis allowing for simultaneous interrogation of multiple signaling pathways in all innate and adaptive immune cell subsets present in a blood sample. The specific aims of the proposed research are anchored in the results of our pilot study showing that Nuclear- Factor-kappa B (NF?B) signaling response to the toll like receptor (TLR) 2 and 4 agonist pg Lipopolysaccharide (pgLPS) is exacerbated in classical monocytes from patients with PD compared to healthy controls. We hypothesize that chronic exposure to periodontal pathogens in patients with PD primes cells for exacerbated pro-inflammatory signaling responses. The specific aims are (1) to develop a novel CyTOF assay to optimally study immune adaptations to PD and (2) to identify cell-specific immune signatures that reflect the plasticity of the innate and adaptive immune responses associated with PD. The study design will involve development of a 43 parameter CyTOF assay for the functional assessment of all major innate and adaptive cell subsets followed by enrollment of 80 patients with and without PD, collection of serial whole blood samples (baseline then three weeks and three months after scaling and root planing), and application of an innovative elastic net algorithm adapted to the analysis of highly inter-related datasets. If successful, we will identify a systemic immune signature characterizing the plasticity of the peripheral immune response to PD. Results will provide the foundation for larger studies identifying predictive immune signatures of systemic complications of PD. This approach could revolutionize PD treatment from local mechanical debridement to targeting of modifiable features of the host's machinery.